One known approach to improve the color reproduction of a color photographic light-sensitive material includes a method which uses a colored coupler. The basic concept of such an approach is described in PSA Journal, Vol. 13 (page 94, 1947). This approach contemplates allowing a colored coupler to mask the deterioration in the color reproduction which is due to the unnecessary side absorption of light by a color forming dye of a coupler which is used in a color film.
However, this approach is disadvantageous because the incorporation of a colored compound in a light-sensitive layer involves a reduction in sensitivity. For example, in order to correct the side absorption of green light by a color forming dye of a cyan coupler, a magenta colored cyan coupler is generally added to the red-sensitive layer itself. It has been found that the absorption of light in the longer wavelength region by this magenta colored cyan coupler causes a shortage of light absorption in the shorter wavelength region of light by the red-sensitive layer. In particular, if a phenol cyan coupler as described in U.S. Pat. Nos. 4,333,999 and 4,451,559 is used as a cyan coupler, such a color forming dye shows much side absorption of light in the longer wavelength region. Therefore, a magenta colored cyan coupler is needed. However, the use of such a colored cyan coupler causes a remarkable reduction in the sensitivity of a red-sensitive layer.
It has also been found that the use of a yellow colored magenta coupler in a green-sensitive layer causes a shortage of light absorption which is necessary in the shorter wavelength region by the green-sensitive layer and hence a reduction in the sensitivity thereof for the same reason as described above.
On the other hand, U.S. Pat. No. 3,672,898 proposes a distribution of spectral sensitivity of blue-sensitive, green-sensitive and red-sensitive layers for more faithful color reproductivity. This approach contemplates shifting the spectral sensitivity of a red-sensitive layer to a shorter wavelength region which overlaps a large part of the spectral sensitivity distribution of a green-sensitive layer. Therefore, if a magenta colored cyan coupler is used in a red-sensitive layer, the absorption by the coupler causes a great shortage of light necessary for the red-sensitive layer which results in problems during the practical use of such a light-sensitive material for photography.
Several approaches have been proposed to solve the above mentioned proposes For example, representative approaches for solving these problems are described in U.S. Pat. Nos. 4,427,763 and 4,555,477. However, it has been found that none of these approaches can be put into practical use because these approaches have a defect in molecular design. That is, in the former patent, precursors of yellow colored magenta couplers are disclosed. However, it is required that these couplers undergo coupling after being hydrolyzed. Therefore, this approach is poor in the speed of color formation. In the latter patent, couplers which allow a ligand for the formation of a complex compound to be separated from the coupling position thereof are disclosed. However, since these couplers need to contain a ligand in the coupling-off group, the range of coupling-off groups which can be selected is limited. As a result, the degree of freedom in selecting the coupling activity becomes small. In particular, if such a compound is used in a highly sensitive photographic light-sensitive negative which requires a highly reactive coupler it leaves much to be desired.
Many studies have been made heretofore to improve the image fastness of a color photographic light-sensitive material. One approach thus developed is to use a metal chelate. For example, U.S. Pat. No. 4,555,478 discloses a compound which cleaves a chelating agent from the coupling position of a coupler. However, it has been found that the compounds described in the above mentioned patent have a low coupling activity and thus are not suitable for use in the current highly sensitive light-sensitive materials.